collar beam vs girder

collar beam

noun
  • A horizontal piece of timber connecting and tying together two opposite rafters. 

girder

noun
  • A beam of steel, wood, or reinforced concrete, used as a main horizontal support in a building or structure. 

  • One who girds; a satirist. 

How often have the words collar beam and girder occurred in a corpus of books? (source: Google Ngram Viewer )